Method and device for the striking of an arc in a reactor

ABSTRACT

The present invention relates to a method and a device for the execution of the method for the striking of an arc between cathode and anode in a reactor for the cracking of hydrocarbons, e.g., for the manufacture of acetylene, the reactor comprising a number of intermediate electrodes arranged between cathode and anode.

nited States Patent Mogensen et a1.

1 1 Jan. 28, 1975 [54] METHOD AND DEVICE FOR THE 2.977.508 3/1961Germeshausen 315/336 X A 3,223,884 12/1965 Ward 315/336 X 3.237.0512/1966 Schober... 315/137 [75] Inventors: Palne Mogensen, Jarfalla; Erik3.238.417 3/1966 B01616 315/323 Smars, Rimho; Mats J. Kaij, Solna.3.351.806 11/1967 Farhcr ct a1. 315/336 X a of Sweden FOREKJ P TENTS ORAPPLIL TIONS L t N A A [73] Asslgnee' AGA Akuebolag 160.233 1/1964U.S.S.R 315/336 [22] Filed: June 28, 1973 [21] Appl. No.: 374,367Primary E.ranziner-A1frcd L. Brody Attorney, Agent. or FirmLerner,David. Littenberg & [301 Foreign Application Priority Data Samuel June29. 1972 Sweden 8537/72 [57] ABSTRACT Cl 315 336, 313 196, 313 308, [52]U 315/623 201/302 The present invention relates to a method and a de-[51] Int Cl b 17/48 vice for the execution of the method for thestriking of [58] Fie'ld 137 360 an arc between cathode and anode in areactor for the "515 5 6 cracking of hydrocarbons, e.g., for themanufacture of acetylene, the reactor comprising a number of inter- [56]References Cited mediate electrodes arranged between cathode and andUNITED STATES PATENTS 0 e 2.957.098 10/1960 Bernstein 315/336 X 4Claims, 1 Drawing Figure CONTROL EQUIPMENT 9 a lGN/T/O/V 1 DEV/CEPATENIEn Mmms CONTROL EQUIPMENT a IGNITION /DEV/CE METHOD AND DEVICE FORTHE STRIKING OF AN ARC IN A REACTOR BACKGROUND OF THE INVENTION At thestriking of the arc in a reactor for the cracking of hydrocarbons, e.g.,at the manufacture of acetylene, problems arise in establishing an arebetween the cathode and the anode when the distance between theseelectrodes is relatively great. It is thus too great for making itpossible to achieve a direct discharge between cathode and anode bymeans of available voltage sources. To make possible the striking, adisplaceable auxiliary electrode has been used until now, which at themoment of striking is brought into contact with the cathode and whichafter an arc to the cathode has been obtained, is moved from the cathodetoward the anode until an arc has come into existence between thecathode and the anode. This method requires mechanical devices which arecomplicated and difficult to handle. Another method that has beenapplied consisted in the use of a thin wire which connects the cathodeand the anode. When voltage is applied between cathode and anode thewire burns off and an arc is formed between the electrodes. Thedisadvantage of this method consists in that before each ignitionprocess a wire has to be fitted between cathode and anode.

SUMMARY OF THE INVENTION It is the object of the present invention toprovide a method and a device which make it possible to achieve a safestriking of the are without the aforementioned disadvantages. The methodis characterized mainly in that one or more of the intermediateelectrodes are given a voltage of the same type as that of the anode,that a striking voltage is applied during a short interval of timebetween the cathode and the intermediate electrode located nearest thecathode, so that during this interval of time an arc is produced betweenthe cathode and the said intermediate electrode, and that thereafter atcertain intervals of time the voltage to the subsequent electrodes isbroken, the arc formed being passed on to the subsequent intermediateelectrode until the arc reaches the anode, whereby a fully formed are isobtained between the cathode and the anode.

DETAILED DESCRIPTION OF THE DRAWINGS In the following the invention willbe described in detail in connection with the enclosed drawing whichshows an embodiment of the method specified. The FIGURE showsschematically a reactor 1 which comprises a cathode 2, a number ofintermediate electrodes 3, 4, 5 and 6 and an anode 7. The cathode andthe anode are connected to a voltage source. Between the cathode 2 andthe nearest intermediate electrode 3 is connected an ignition device 8that can be switched on and off. This can consist, e.g., of a highfrequence ignition device or a spark discharge ignition device. In theembodiment shown each of the intermediate electrodes is connected via abreak contact 15, 16, 17 and 18 to the same pole on the voltage sourceas the anode 7. The break contacts are worked upon by relay deviceswhich can be constituted of for example the contactors l0, l1, l2 and I3respectively. The ignition device 8 and the contactors l0 13 areinfluenced by a control equipment 9 which comprises a number oftimecontrolled coupling members, e.g., time relays. The time relays arearranged so that in the first place a con- LII trol signal istransmitted to the ignition device 8 which is switched on during a briefinterval 'of time. During this an arc is formed between the cathode 2and the nearest intermediate electrode 3. Thereupon the time relays byturn switch on the contactors 15-18. In doing this the voltage is firstswitched off by the contact 15 to the intermediate electrode 3, as aresult of which the arc is passed on to the intermediate electrode 4.The voltage to the electrode 4 is then switched off by means of thecontact I6, the arc being passed on to the intermediate electrode 5. Inthis manner the voltage is successively switched off to the intermediateelectrodes, so that when the voltage has been switched off to the lastintermediate electrode 6 by means of the contact I8, the arc is passedover to the anode 7. In this manner a fully developed arc has beengenerated between the cathode and the anode. In the circuits locatedclosest to the cathode a reactance coil 14 is connected between theanode and the respective intermediate electrode. This inductance is sodimensioned that high frequency interferences are suppressed, and thatthe current is given a suitable rise time.

In the embodiment shown in the FIGURE all the intermediate electrodesare connected to the same pole on the voltage source as the anode 7. Itis not always necessary, however, to have this arrangement; it may besufficient for example to have only one or some of the intermediateelectrodes connected to the anode depending upon the distance betweencathode and anode. The effect will still be satisfactory with a rapidlydeveloped arc between cathode and anode.

In certain circumstances the cathode can at the instant of striking beadvanced towards the anode so that the cathode is enclosed by thenearest intermediate electrode. In this case the ignition device isconnected between the two nearest intermediate electrodes and an arc isproduced between these electrodes and the cathode. The arc is thenpassed on towards the anode in the manner as described earlier, as thecathode is moved backwards from the first intermediate electrode.

By means of the method and the devices for the execution of the samementioned above a striking system has thus been obtained which operatesautomatically, which is quick and effective and which gives a reliablestriking of the arc.

The method described in the foregoing is not limited to a reactor forthe manufacture of acetylene but other areas of application are quiteconceivable within the scope of the invention. Likewise the device forthe execution of the method can be given a different form from thatdescribed. Thus the ignition device as well as the making and breakingdevices and the control equipment may bev given different forms ofrealization.

What is claimed is:

l. A method for the striking of an arc between a cathode and an anode ina reactor comprising the steps of providing a number of intermediateelectrodes arranged between cathode and anode in the reactor, providingthe intermediate electrodes with a voltage similar to that provided theanode, applying a striking voltage during a brief interval of timebetween the cathode and the intermediate electrode closest to thecathode, so that during this interval an arc is produced between thecathode and a first intermediate electrode, and subsequently at certainintervals of time, switching off the voltage to the first intermediateelectrode and switching on the voltage to the following voltageenergized intermediate electrode, the are formed being passed on to thefollowing intermediate electrode until it reaches the anode. as a resultof which a fully developed arc is obtained between cathode and anode.

2. Apparatus comprising a reactor, a cathode and an anode passing withinsaid reactor and spaced one from another. intermediate electrodes spacedone from another along a path between said cathode and anode and spacedfrom said cathode and anode, control means for applying a common voltageto said intermediate electrodes and said anode, striking voltage controlmeans for applying a striking voltage between the cathode and theintermediate electrode closest to the cathode. and switching meansassociated with said control means for switching off in time sequentialrelation the voltage to said intermediate electrodes starting with theintermediate electrode closest to said cathode and then switching offvoltage to the next closest intermediate electrode whereby the arcformed between the first intermediate electrode and the cathode ispassed on to the next closest intermediate electrode until it reachesthe anode. as a result of which a fully developed arc is obtainedbetween cathode and anode.

3. Apparatus in accordance with claim 2 including high frequency dampingmeans operative between each intermediate electrode and said controlmeans to suppress high frequency interference and to give a suitablerise time to current in the intermediate electrode circuit.

4. The device in accordance with claim 3 wherein said high frequencydamping means is an inductor.

1. A method for the striking of an arc between a cathode and an anode ina reactor comprising the steps of providing a number of intermediateelectrodes arranged between cathode and anode in the reactor, providingthe intermediate electrodes with a voltage similar to that provided theanode, applying a striking voltage during a brief interval of timebetween the cathode and the intermediate electrode closest to thecathode, so that during this interval an arc is produced between thecathode and a first intermediate electrode, and subsequently at certainintervals of time, switching off the voltage to the first intermediateelectrode and switching on the voltage to the following voltageenergized intermediate electrode, the arc formed being passed on to thefollowing intermediate electrode until it reaches the anode, as a resultoF which a fully developed arc is obtained between cathode and anode. 2.Apparatus comprising a reactor, a cathode and an anode passing withinsaid reactor and spaced one from another, intermediate electrodes spacedone from another along a path between said cathode and anode and spacedfrom said cathode and anode, control means for applying a common voltageto said intermediate electrodes and said anode, striking voltage controlmeans for applying a striking voltage between the cathode and theintermediate electrode closest to the cathode, and switching meansassociated with said control means for switching off in time sequentialrelation the voltage to said intermediate electrodes starting with theintermediate electrode closest to said cathode and then switching offvoltage to the next closest intermediate electrode whereby the arcformed between the first intermediate electrode and the cathode ispassed on to the next closest intermediate electrode until it reachesthe anode, as a result of which a fully developed arc is obtainedbetween cathode and anode.
 3. Apparatus in accordance with claim 2including high frequency damping means operative between eachintermediate electrode and said control means to suppress high frequencyinterference and to give a suitable rise time to current in theintermediate electrode circuit.
 4. The device in accordance with claim 3wherein said high frequency damping means is an inductor.